DLX3 Inhibits the Proliferation of Human Dental Pulp Cells Through Inactivation of Canonical Wnt/β-Catenin Signaling Pathway
DLX3 Inhibits the Proliferation of Human Dental Pulp Cells Through Inactivation of Canonical Wnt/β-Catenin Signaling Pathway
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DLX3 通过失活经典 Wnt/β-连环蛋白信号通路来抑制人牙髓细胞的增殖
DOI：
10.3389/fphys.2018.01637
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发表时间：
2018-11-20
影响因子：
4
通讯作者：
Yang, Guobin
中科院分区：
文献类型：
--
作者：
Zhan, Yunyan;Li, Xiaoyan;Yang, Guobin
同源域基因 Distal-less-3 (Dlx3) 在牙齿发育过程中发挥着重要作用。我们之前的研究表明DLX3抑制人牙髓细胞（hDPC）的增殖。然而，DLX3调节hDPC增殖和维持细胞静止的机制仍不清楚。鉴于经典 Wnt 信号在牙髓细胞增殖和牙齿发育中的重要性，我们假设 DLX3 通过失活经典 Wnt 信号来抑制 hDPC 的增殖。通过在原代 hDPC 中过表达或敲低 DLX3，我们发现 DLX3 下调了经典 Wnt 信号传导及其下游靶基因。当用氯化锂处理DLX3过表达的细胞时，DLX3的增殖抑制作用被逆转。我们还发现DLX3增强了DKK1的表达，并且DLX3导致的hDPC增殖减少随着DKK1的敲低而逆转。此外，荧光素酶报告基因检测和染色质免疫沉淀检测显示DLX3能够结合Dkk1启动子区域（nt）-1656至-1245，并刺激Dkk1启动子活性。诱变研究进一步揭示了 Dkk1 启动子中的两个 DLX3 响应元件。综上所述，我们的数据表明，DLX3 通过直接结合 Dkk1 启动子并增加其表达来灭活 Wnt/β-catenin 信号通路，从而抑制 hDPC 的增殖。
Homeodomain gene Distal-less-3 (Dlx3) plays an important role during tooth development. Our previous studies indicate that DLX3 inhibits proliferation of human dental pulp cells (hDPCs). However, the mechanism of DLX3 regulating proliferation of hDPCs and maintaining the quiescence of the cells remain unknown. Given the importance of canonical Wnt signaling in the proliferation of dental pulp cell and tooth development, we hypothesized that DLX3 inhibited proliferation of hDPCs through inactivation of canonical Wnt signaling. With overexpression or knock-down of DLX3 in primary hDPCs, we found DLX3 down regulated canonical Wnt signaling and its downstream target genes. And when the DLX3 overexpressed-cells were treated with lithium chloride, the proliferation inhibition by DLX3 was reversed. We also found that DLX3 enhanced the expression of DKK1 and the reduced proliferation of hDPCs by DLX3 was reversed with knock-down of DKK1. Furthermore, luciferase reporter assay and chromatin immunoprecipitation assay showed DLX3 was able to bind to Dkk1 promoter region from nucleotides (nt) -1656 to -1245, and stimulated Dkk1 promoter activity. Mutagenesis studies further revealed two DLX3 responsive elements in Dkk1 promoter. Taken together, our data indicate that DLX3 inhibits proliferation of hDPCs via inactivation of Wnt/β-catenin signaling pathway by directly binding to Dkk1 promoter and increasing its expression.